Method of treating twister gears for wire fabric-making machines



. W. W. DE LAMATTER Aug. 17, 1943. Y

METHOD OF TREATING TWISTER GEARS FOR WIRE FABRICJIIAKING MACHINES Filed Jan. 25, 1940 FIG. 1.

PIE. 4. l- |[5.5,

Patented Aug. 17, 1943 IMETHOD OF TREATING TWIS TER GEARS FOR WIRE FABRIO-lvllAlKlNGr MACHINES lvilliam W. De Lamatter, Cleveland, Ohio, as-

signor to The American Steel and Wire Company of New Jersey, a corporation of New Jersey 'Application January 25, 1940, Serial No. 315,591

4 Claims.

with a toothed periphery interrupted by a slot extending radially to the axis of the gear or slightly beyond. This. slot is adaptedto receive two or more wires which are then intertwisted upon rotation ofthe gear. The. metal of the twister gearwears rapidly atthe bottom of the slot because this is where thewires bear while they are being intertwisted, the remainder of the slot functioning only to guide the wires to the slot bottom. Heretofore, a twisterg'ear was discarded when it became worn in this manner. I

According to the present invention, such a worn twister gear is first annealed in a furnace at about 2100 Fahrenheit in areducing atmosphere, for about 15 minutes, this giving the gear a bright anneal. After being so heated for this 15 minute period, it is removed and placed in a cooling chamber where it is kept for about 30 minutes, this cooling chamber also being supplied with a reducing atmosphere and the gear there cooling to below its oxidation point, whereby it comes out bright.

Next, a hole is drilled axially through the gear, this hole being about of an inch in diameter so that the drilling serves to remove all of the worn metal surrounding the bottom of the gear slot. Then a cylindrical tantalum carbide insert, approximately of an inch in diameter and about .16 of an inch high, is press-fitted into the hole drilled through the gear. This insert has a rough radial slot opening from its periphery and extending to or beyond its axis, and this slot is, in each instance, aligned with the remaining portion of the gear slot remaining after the drilling.

A curved piece of copper wire in the form of a curl of about the same diameter as the diameter of the hole drilled through the gear, is now tied in the hole of the gear so it covers the juncture between the insert and the gear, the tying being done by means of a loop of stainless steel wire bent around the bottom of the slot of the insert and the opposite periphery of the gear. The curl of copper wire serves as brazing metal, and it is necessary that the gear, the insert and the copper wire be perfectly clean and free from oxides or grease.

Brazing. is eiiected by placing the gear in a brazing furnace, the gear being positioned with the copper curl uppermost. In the brazing furnace, the gear is heated to approximately 2100" Fahrenheit for about 15 minutes, the copper wire melting during this time and running down so as to completely fill all of the space between the press-fitted parts of the insert'and the gear. The gear is subsequently placed in a cooling chamberiuntil it cools to a nonoxi izing temperature, both the brazing furnace and this cooling chamber being provided with a reducing atmosphere so that the gear comes out bright.

"It is the inventors opinion that the brazed jointprovided by the above procedure results in a metal juncture comprising alloys of copper and iron and of copper and tantalum carbide.

However, regardless of the correctness of this opinion, the insert'is permanently-fixed in the hole drilled in the gear and there is no unfilled space between the insert and the gear at any point.

Upon cooling sufiiciently,'the stainless steel tie wire is cut off, it being understood that the temperature to which the gear is heated is insufficient to result in melting of either the gear or stainless steel tie wire.

At this time, the gear is carburized in a molten cyanide salt bath where it is kept at a temperature of about 1500" to 1600 Fahrenheit for one or two hours. Upon completion of this carburizing treatment, the gear is quenched in water,

this leaving the gear case-hardened to a hardness of from 50 to 55 C. Rockwell.

, Ultimately, the case-hardened gear is further treated by lapping or polishing the metal bounding its slot, this being done either with a copper disk using an abrasive powder, such as boron carbide or diamond dust, or by means of a rub ber wheel impregnated with diamond grit. Since there is no space between the insert and the gear, this operation results in a perfectly continuous and polished surface on either side of the gear slot.

The foregoing is illustrated by the accompanying drawing, in which:

Figure 1 is a front view of a worn twister gear;

Figure 2 shows the same with the hole drilled;

Figure 3 shows the same with the insert in place and the brazing metal tied;

Figure 4 is a section taken from the line IV-IV in Figure 3;

Figure 5 shows the insert braced in place with tie removed, and

Figure 6 shows the final result.

in the hole and with the copper curl 5 tied in place by means of a loop =01 stainless steel Wire 6. After the brazing step and the removal or stainless steel tie wire, the gear appears as shown by Figure 5, the brazed joint being indicated at I;

3. A method of treating a wire fabric-making machine twister gear, comprising drilling a hole axially through said gear to remove metal surrounding the gear slot bottom, press-fitting a,

metal carbide cylindrical insert having a radial slot into said hole with its slot aligned with the remainder of the gear slot, tying a curved copper wire in said hole on said insert at the juncture of the two with stainless steel wire, placing said gear in a furnace so as to heat the same to a.

temperature above the melting temperature of copper and below the melting temperature of stainless steel and of the gear metal, and sub- The finished gear appears as shown by Figure 6, p

it now being case-hardened by cyaniding and the bounding walls'of the slot finished by grind-in and polishing, as required.

I claim:

1. A method or treating-a twister gear for a wire fabric-making machine, including forming a hole axially "through the gear, placing a hard metal insert in this hole fixing the insert permanently in the hole by placing a curved at the juncture of the insert and gear, tying this curved wire in place with wire having a higher melting temperature than the mn'ved wire and heating the gear to .a temperature above the melting temperature of the curved wire and below the melting temperature of thetying wire.

2. A method of reconditioning a wire fabricmaking machine twister gear that is worn at the of its :slot, including removing metal smrounding the slot bottom to provide an opening, placing an insert a radial slot in this opening, aligning its slot with the remainder of the twister gear slot, and cementing this insert permanently in place with metai,

sequently grinding and polishing the complete gear slot as required to obtain a satisfactory finish 4. A method of treating a wire fabric-making machine twister gear, comprising drilling a hole axially through said gear to remove metal surrounding the gear slot bottom, press-fitting a metal carbide cylindrical insert a radial slot into said hole with its slot aligned with the remainder of the gear slot, tying a curved wire in said hole on said insert at the jimcture of the two with stainless steel wire, placing said gear in a furnace so as to heat the same to a'tempenture above the melting temperature of copper and below the melting temperature of stainless steel and of the gear metal, and subsequently grinding and polishing the comphete gear slot as required to obtain a satisfactory finish, said gear being positioned in said furnace with said copper wire uppermost so the melting copper runs down into the space between the press-fitted portions of said insert and gear, whereby the complete gear slot has continuous surfaces.

W. m: LAMATTER. 

